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Post by Telemachus on Mar 2, 2019 19:54:58 GMT
But it's connected to a stud fitted to the hull next to my battery negative terminal hull bonding stud. You've already pointed out that I can't refer to the battery negative connection as "earth", So why is it ok to call the inverter earth connection "Earth" when they are effectively connected to the same point? Just asking đ¤ Itâs a perfectly reasonable question! The inverter earth connection is a protective earth. As Iâm sure you know, the purpose is to ensure that if someone touches a mains live terminal and earth, the RCD will trip and hopefully save their life. Ditto if a fault condition occurs inside an appliance, cable gets chafed etc. The same earth that is in a house wiring, for the same purposes. So whilst it could be argued that there isnât an earth on a boat (unless you are a vampire), it is nevertheless reasonable to use the exact same terminology as used in houses, on the boat, because the function is identical. The reason for bonding the 12v negative to hull is a different one, nothing to do with personal safety. If the same terminology is used, there is confusion about the purpose especially when hull bonding is confused with hull return (something which is used on vehicles but shouldnât be used on boats, and more confusingly, if these 3 things are all given the same word âearthâ despite the 3 completely different functions. Yes they are all wires connected to hull, but there the similarity ends.
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Post by Telemachus on Mar 2, 2019 19:56:04 GMT
Boats donât have what you misguidedly call âearth returnsâ so I can only assume that your repeated use of the term in the context being discussed is due to your creeping dementia. Careful Nick, or you'll be receiving a letter from his imaginary no-win, no-fee libel lawyer. Unlikely as he canât remember who his lawyer is!
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Post by TonyDunkley on Mar 2, 2019 20:15:53 GMT
But it's connected to a stud fitted to the hull next to my battery negative terminal hull bonding stud. You've already pointed out that I can't refer to the battery negative connection as "earth", So why is it ok to call the inverter earth connection "Earth" when they are effectively connected to the same point? Just asking đ¤ . . . . . . . . . there isnât an earth on a boat (unless you are a vampire) . . . . . . . . . . and: . . . . . . . . . . . . hull return (something which is used on vehicles) . . . . . . Losing the plot completely, . . aren't you Nick ? Animals such as foxes and badgers live in 'earths' - not vampires, . . and apart from the likes of DUKW's, vehicles tend not to have hulls !
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Post by Telemachus on Mar 2, 2019 21:14:18 GMT
. . . . . . . . . there isnât an earth on a boat (unless you are a vampire) . . . . . . . . . . and: . . . . . . . . . . . . hull return (something which is used on vehicles) . . . . . . Losing the plot completely, . . aren't you Nick ? Animals such as foxes and badgers live in 'earths' - not vampires, . . and apart from the likes of DUKW's, vehicles tend not to have hulls ! Yes Rachael, whatever you say. <Nurse!!>
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Post by Mr Stabby on Mar 2, 2019 21:20:37 GMT
. . . . . . . . . there isnât an earth on a boat (unless you are a vampire) . . . . . . . . . . and: . . . . . . . . . . . . hull return (something which is used on vehicles) . . . . . . Losing the plot completely, . . aren't you Nick ? Animals such as foxes and badgers live in 'earths' - not vampires, . . and apart from the likes of DUKW's, vehicles tend not to have hulls ! Errr, look Tony, I think we can all see who the clueless fuckwitted loser in this debate is. Now why don't you just stop digging?
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Post by JohnV on Mar 2, 2019 21:22:29 GMT
But it's connected to a stud fitted to the hull next to my battery negative terminal hull bonding stud. You've already pointed out that I can't refer to the battery negative connection as "earth", So why is it ok to call the inverter earth connection "Earth" when they are effectively connected to the same point? Just asking đ¤ So whilst it could be argued that there isnât an earth on a boat (unless you are a vampire), it is nevertheless reasonable to use the exact same terminology as used in houses, on the boat, because the function is identical. The original term for the third wire in a single phase 240 volt system was the CPC (circuit protective conductor) but it is now called the earth wire. in IET publications As most boats have 240 volt systems and are wired using three conductors they must have an earth circuit.
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Post by Telemachus on Mar 2, 2019 21:25:41 GMT
So whilst it could be argued that there isnât an earth on a boat (unless you are a vampire), it is nevertheless reasonable to use the exact same terminology as used in houses, on the boat, because the function is identical. The original term for the third wire in a single phase 240 volt system was the CPC (circuit protective conductor) but it is now called the earth wire. in IET publications As most boats have 240 volt systems and are wired using three conductors they must have an earth circuit. Correct-ish, but whatâs your point? i say -ish because itâs not really a circuit.
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Post by JohnV on Mar 2, 2019 21:34:15 GMT
not ish because that is the terminology used by IET and it is a circuit .... if it wasn't it couldn't act as a protective circuit.
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Post by Telemachus on Mar 2, 2019 21:41:34 GMT
not ish because that is the terminology used by IET and it is a circuit .... if it wasn't it couldn't act as a protective circuit. I suppose itâs a moot point but a circuit normally allows current to flow around a loop. The general idea of an earth connection is that current doesnât flow through it because the circuit isnât made. It is only made under fault conditions.
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Post by JohnV on Mar 2, 2019 21:43:08 GMT
not ish because that is the terminology used by IET and it is a circuit .... if it wasn't it couldn't act as a protective circuit. I suppose itâs a moot point but a circuit normally allows current to flow around a loop. The general idea of an earth connection is that current doesnât flow through it because the circuit isnât made. It is only made under fault conditions.when the current flows round in a loop
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Post by JohnV on Mar 2, 2019 21:45:35 GMT
does that mean the an earth circuit on a boat is like Shrodinger's cat ?
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Post by Clinton Cool on Mar 2, 2019 23:55:43 GMT
I've never understood much about electricity. That's probably obvious from my question earlier in this thread. 240v at home; positive, negative and earth. I understand that positive and negative are needed to make a circuit. Earth? that was something to do with safety I think, never tried to understand it, I'd rather go kayaking or something.
Now then, boats: nice and simple I thought, there are only 2 wires. Usually red is positive and black is negative. Connect both to what you are connecting and you have a circuit. Simples. Sometimes people talk about 'earth' though, this confuses me. How can there be an earth when there are only 2 cables, positive and negative? And anyway, unless you're out for blacking how can you connect to 'earth' when you're floating in a muddy ditch?
I think I now know that negative and earth are mostly interchangeable terms.
I've also heard people talk of +ve and -ve. I'm going to hazard a guess that +ve is positive and -ve is negative. Why not just call them positive and negative, why complicate thing for relative numpties?
Overall I think things would be much better if everyone agreed one on term to describe something.
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Post by Telemachus on Mar 3, 2019 0:04:26 GMT
I've never understood much about electricity. That's probably obvious from my question earlier in this thread. 240v at home; positive, negative and earth. I understand that positive and negative are needed to make a circuit. Earth? that was something to do with safety I think, never tried to understand it, I'd rather go kayaking or something. Now then, boats: nice and simple I thought, there are only 2 wires. Usually red is positive and black is negative. Connect both to what you are connecting and you have a circuit. Simples. Sometimes people talk about 'earth' though, this confuses me. How can there be an earth when there are only 2 cables, positive and negative? And anyway, unless you're out for blacking how can you connect to 'earth' when you're floating in a muddy ditch? I think I now know that negative and earth are mostly interchangeable terms. I've also heard people talk of +ve and -ve. I'm going to hazard a guess that +ve is positive and -ve is negative. Why not just call them positive and negative, why complicate thing for relative numpties? Overall I think things would be much better if everyone agreed one on term to describe something. Curateâs egg. No, at home not positive, negative and earth. Itâs AC. Yes, boat DC system just red and black, there is no earth. No, negative and earth not the same thing, see above. +ve seems an obvious abbreviation for positive to me, but if not obvious then sorry. Did you know that etc was short for et cetera, kg was short for kilogrammes etc (which, as I mentioned, is short for et cetera). Yes everyone could agree to one term to describe something. I guess that term would be âthingâ. But it might get a little confusing eg (short for âfor exampleâ) âplease pass me that thing so I can adjust this thing in order that the main thing works properly so that the thing will move once againâ. Are you still sure that is much better?
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Post by Clinton Cool on Mar 3, 2019 0:39:15 GMT
I've never understood much about electricity. That's probably obvious from my question earlier in this thread. 240v at home; positive, negative and earth. I understand that positive and negative are needed to make a circuit. Earth? that was something to do with safety I think, never tried to understand it, I'd rather go kayaking or something. Now then, boats: nice and simple I thought, there are only 2 wires. Usually red is positive and black is negative. Connect both to what you are connecting and you have a circuit. Simples. Sometimes people talk about 'earth' though, this confuses me. How can there be an earth when there are only 2 cables, positive and negative? And anyway, unless you're out for blacking how can you connect to 'earth' when you're floating in a muddy ditch? I think I now know that negative and earth are mostly interchangeable terms. I've also heard people talk of +ve and -ve. I'm going to hazard a guess that +ve is positive and -ve is negative. Why not just call them positive and negative, why complicate thing for relative numpties? Overall I think things would be much better if everyone agreed one on term to describe something. Curateâs egg. No, at home not positive, negative and earth. Itâs AC. Yes, boat DC system just red and black, there is no earth. No, negative and earth not the same thing, see above. +ve seems an obvious abbreviation for positive to me, but if not obvious then sorry. Did you know that etc was short for et cetera, kg was short for kilogrammes etc (which, as I mentioned, is short for et cetera). Yes everyone could agree to one term to describe something. I guess that term would be âthingâ. But it might get a little confusing eg (short for âfor exampleâ) âplease pass me that thing so I can adjust this thing in order that the main thing works properly so that the thing will move once againâ. Are you still sure that is much better? Sod it I'm going surfing, my brains hurts
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Post by Deleted on Mar 3, 2019 5:59:54 GMT
My boat is wired with positive feeds and negative returns, nothing going to the Hull, though there may be a wire to ground in the outboard. Should I have a negative bond to the Hull in this case? I can't see the need electrically. I also have a 1.2k inverter, how does this affect the situation. Boat is due first BSC after major works shortly so I may need to make alterations. This is a good question. Nick has answered why you might need an earth connection to a (metal) hull if you are using 240v (i.e inverter). Basically for personal safety and effectiveness of the RCD. I think the reason why many boats (particularly with metal hulls) donât have a connection between the hull and negative of the 12 volt circuit is to avoid corrosion of the hull due to the electrochemical effects of placing a charge on the hull. What is a bit confusing is that some engines are connected electrically to metal hulls through the way they are mounted to the hull. If a12 volt engine electrical component, like the alternator, has a connection between the negative and casing then you may have inadvertently also made that connection between the negative of the 12 volt circuit and the hull. Would I be correct in saying that a âmarinisedâ alternator has no internal connection between the case and negative connections for this reason?
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